Check valve



H. M. NICHOLSON CHECK VALVE Filed June 19, 1935 NVENTOP Mam ATTORNEY Patented May 24, 1927.

ZPATENTOFFICE'.

HOWARD M.1NICHOLSON,OF PITTSBURGH, PENNSYLVANIA..

eHEcK VALVE.

Application filed me s, 1925. senaino. 38,183.

Myinvention relates to check valves, that is, to valves of'the type adapted to permit 'theflow of fluid through the valve in one direction but to oppose the flow of'such' fluid through the valve in the opposite direction. V

Check valves embodying my invention LI'G particularly adapted for, though in no way'hn'nted to, use as foot valves in connec-l 1 tion with pumps, such as used for dispensing I I will describe one form of checkvalve embodying my inventionand will then point out the novel features thereof in claim.

In the accompanying drawing, Fig. 1 is a vertical sectional view showing'one form of 'checkvalve embodying my invention with the valve closed. Fig. 2 is a view showing the valve illustrated in Fig. 1 with the valve "open. fFig. 3 is'a sectional view along the line IIL-III of Fig. 2. Fig. 4 is a view, partly diagrammatic, showing one form of gasoline dispensing apparatus in which is incorporated the valve shown in the preceding. views.

ilar parts in each of'the several views."

Referring first to Fig. 1, the valve, desig nated in general by the reference character V, comprises a casing A of suitable shape and material. As here shown this casing is cylindrical. The top plate A of this casing is provided with an outlet opening, here shown as a pipe 1. Extending upwardly in the casing A is a frusto conical valve seat 2 having its faces sloping inwardly toward an inlet opening 3 in the top of the seat. The lower edge of the seat 2 is attached to the casing A at its bottom, aswill be plain from the drawing. .A mass of mercury 7 is introduced into the casing A and occupies the annular space around the lower edge of the seat 2.

'Resting freely on seat 2 is a frusto conicalvalve cap 4. tioned that when the flat top i of cap l rests on the top of the valve seat 2, theside walls of the valve cap are spaced from the slant faces of the valve seat by a very small annular. clearance space or passagefi. Under this condition the lower-edge 6 of the valve cap is immersed in the mercury 7. If now a fluid is admitted to thelvalve through pipe l, which fluid tends toflow through the Similar reference characters refer to si1n- The parts are so propor valve to opening 3 in valve seat 2, therpressure'exerted on this fluid is transmitted to the nercury 7 and forces the mercury ,into the passage: 5; between the cap land the "seat 2. The mercury in this passage 1111811 rises to a level 7 sufiicient to create a static head which is equal to the pressure tending to force the fluid through the valve. Be-

cause of the high specific" gravity of metcury, a head of a few inches of mercury in the passage 5 of the valve is sufficient to prevent the flow of some light I fluidgsuch 1 as gasoline, under a pressure of many feet of such fluid.

Referring now to Figs. Q'and 3, when fluid is forced into the valve through the inlet opening 8 by pressure which tends to cause a flow of such fluid to outlet pipe 1, this pressure lifts cap 4 upwardly out of engagement with the valve seat. Motion of the cap upwardly is limited by a strap metal guard 8 attached to the under side of top plate A. The parts are so proportioned that when the capis in its extreme upper nular space betweenthe seat and the cap is valve is possible, the mercury "7, of course,

position, the cross-sectional area of the an falling into the pocket between the lower edge 7 of the seat 2 and the casing A. The level of the mercury is then well below the lower edge of the cap 4. An unrestricted path is thereby provided for the fluid to flow upwardly through the valve from inlet opening 3, downwardly between the cap 4 and the seat 2, and upwardly between the cap 4 and the'casing A, to pipe 1.

Should the flow of the fluid be reversed, the cap 1 would immediately return to the position inwhich it is illustrated in Fig. 1,

and the mercury 7 would lee-forced into the restricted clearance space betwen the cap and the valve seat to oppose flow of the fluid j in the reverse direction. v

One advantage of a check valve embody ing my invention is that when the valve is open to permit the flow of flui-d therethrough, a substantially unrestricted path is provided for such fluid, but that when the fluid tends to flow through the valve in the opposite direction the passage 5 between the cap 4 and the seat 2 is diminished and a comparatively small volume of mercury is therefore suflicient to maintain a substantial static head to oppose flow of fluid through the valve in the latter direction. V

In Fig. 4: the reference character P designates a simple form of pump, such asisused for dispensing gasoline. The gasoline is contained in a storage tank T, usuallv buried below the Surface of the ground The casingA of a valve V similar to that shown in Figs. 1, 2 and '3, is placed in the tankT, immersed in the gasoline therein, and the outlet ,pipe 1 is connected with the cylinder 17 of the pump P, This cylin'der contains a piston 11 attached to a rod 12 operated. by a crank 10 throughsuitable gearing. The piston 11 is provided with a port 14 and a flap valve co-operating therewith.

hen handle lO of'the pump P is operated to move the piston upwardly, gasoline is drawn from the tank, through. the valve V-and pipe 1 into cylinder 17. hen the crank 10 is next operated to move the piston '11 downwardly, the check valve V prevents the return of fluid to the tank, and .fiap valve 13 on piston 11 lifts so that the gasoline flows through port 14 to the cylinder 17 above the piston. On the next upstroke of the piston 11, valve 13 closes, and while gasoline is drawn from the tank into the cylinder below the piston, the gasoline above the piston isdischarged through pipe 15 to the dispensing nozzle 16. The cylinder 17 and the stroke of the piston 11 are so proportioned that each operation of the pump discharges a measured quantity of gasoline to the nozzle 16. Obviously, with such an arrangement, it is desirable that the maybe used wherever it is desired to permit the flow of a fluid through a valve in one direction but to prevent such flow in the opposite direction. 7

Although I have herein shown and described only one form of check valve embodying my invention, it is understood that various changes and modifications may be made therein withinthe scope of the appended claim without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

A valve comprising a casing provided at its top with an outlet opening, an upstanding conical seat in the casing having an inlet opening in its top, a mass of mercury in the casing surrounding the base of the seat, and a frusto-conical cap having a flat top adapted at times to engage the top of the seat and having side walls parallel throughout the length of the cap to the walls of the seat but spaced from the seat by an annular air gap, the lower edge of the cap being immersed in the mercury when the cap rests upon the seat.

In testimony whereof I attix my signature.

HOIVARD M. NICHOLSON. 

